1. Field of the Invention
The invention generally relates to noise suppression.
2. Background
Headphones and headsets (referred to collectively hereinafter as “headsets”) that include noise reduction functionality are intended to provide greater speech and/or music quality in noisy environments. Such headsets (referred to hereinafter as “noise reduction headsets”) may be used in conjunction with telephones (e.g., cellular phones, landline phones, or voice-over-internet-protocol (VoIP) phones), computer dictation devices, portable music players, etc. For example, the headsets may be used during air travel to listen to music or for making phone calls while driving. When the headsets are used, any microphones that are included in the underlying devices to which the headsets are attached traditionally are disabled.
Noise reduction headsets that are used for purposes of communication often include a primary microphone (a.k.a. a speech microphone) for detecting speech of a user and a secondary microphone (a.k.a. a noise reference microphone) for detecting noise that may interfere with accuracy of the detected speech. A signal that is received by the primary microphone is referred to as a primary signal. In practice, the primary signal usually includes a speech component (e.g., a user's speech) and a noise component (e.g., background noise). A signal that is received by the secondary sensor is referred to as a secondary signal. The secondary signal usually includes reference noise (e.g., background noise), which may be combined with the primary signal to provide a speech signal that has a reduced noise component, as compared to the primary signal.
More recently, mobile communication device handsets have been developed that include noise reduction functionality. Such handsets often include a primary microphone and a secondary microphone that function as described above with reference to noise reduction headsets. However, any microphones that are included in the handsets traditionally are disabled when headsets are used in conjunction with the handsets.
The relatively close proximity of a primary microphone and a secondary microphone in either a handset or a headset may result in distortion of a speech signal upon performance of a noise reduction operation. For example, the primary signal may include some aspects of reference noise, and/or the secondary signal may include some aspects of the speech signal. In accordance with this example, performance of the noise reduction operation may remove a portion of a speech component of the speech signal. Also, incorporating noise reduction functionality (e.g., a secondary microphone, other hardware, and/or software) into a headset often increases complexity and/or cost of the headset.